In various applications of refrigerant circuits of compression refrigerators known in the related art, a refrigerant collector is disposed next to a heat exchanger, which is operated as an evaporator, in the flow direction of refrigerant. The refrigerant collector, which is disposed next to the evaporator and is referred to as an accumulator, serves as a separator used to store a refrigerant and separate the phase of the refrigerant discharged from the evaporator, in which case the refrigerant is a two-phase mixture formed of gas refrigerant and liquid refrigerant. In addition, the accumulator is used to dry and filter a refrigerant. In typical and conventional refrigerant circuits, particularly refrigerant circuits used for heat pump systems, a compressor is disposed next to an accumulator in the flow direction of refrigerant, and the compressor drops the pressure of refrigerant in the accumulator when the refrigerant circuit is first operated. In particular, when a large amount of liquid is present in the accumulator, the temperature of the liquid is not decreased at the same rate as a saturation temperature related to the pressure of refrigerant. As a result of the pressure drop, the boiling temperature of the refrigerant stored in the accumulator is often lowered more quickly than the temperature of liquid refrigerant. Hence, the refrigerant is present as a superheated liquid that can be suddenly evaporated due to an already low impulse. The sudden evaporation of superheated liquid refrigerant, which refers to a retardation of boiling, causes the liquid refrigerant to be suddenly changed to a gas refrigerant, which may lead to a significant decrease in density. The decrease in density is related to an extreme increase in inherent capacity again. Subsequently, the sudden increase of the pressure in the accumulator, which is caused by the extreme increase in inherent capacity, generates a pressure wave flowing in the whole refrigerant circuit of the system. Such a pressure wave causes vibration and unintended noise again. The pressure increase may sound like explosion depending on the intensity of the pressure and may be detected, particularly in the vicinity of the accumulator depending on vibration. Moreover, the variation in pressure and the vibration apply a significant load to the refrigerant circuit or the parts of the compression refrigerator, and therefore the parts may be damaged. In the retardation of boiling, typical containers, each having a high surface quality but having a small wetted surface area, has a very weak resistance.
For example, the above-mentioned accumulator is disclosed in U.S. Pat. No. 5,970,738. The accumulator has a J-shaped pipe formed at the outlet thereof in order to suck gas refrigerant and liquid oil, and the pipe is disposed in the housing of the accumulator. The pipe may at least come into local contact with the liquid phase of the fluid. The J-shaped pipe is generally smooth for recirculation of gas refrigerant from the accumulator to the compressor. The surface area of the pipe coming into contact with liquid refrigerant may not ensure that gas bubbles are formed enough to block an imminent retardation of boiling to a desired extent.
In order to prevent noise caused by the retardation of boiling and noise such as a sound of explosion in the accumulator, U.S. Pat. No. 6,389,842 discloses an accumulator including an outlet pipe having an increased flow cross section. The accumulator includes a J-shaped refrigerant outflow line disposed therein, and the refrigerant outflow line has a locally increased cross section and also has an addition capacity at the outlet or inlet thereof. When a compressor, which is disposed next to the accumulator in the flow direction of refrigerant, is switched on at an equal operating point, the drop of the pressure in the accumulator is delayed compared to an accumulator which does not have an increased flow cross section. Furthermore, the increase in flow cross section causes a lower flow velocity of refrigerant. As a result, when the compressor is switched on, the liquid refrigerant in the refrigerant outflow line is evaporated and the risk of the retardation of boiling is reduced. However, when the above-proposed solution is used, only a pressure drop process is delayed and the superheating of liquid is slightly reduced. It is impossible to actively introduce the retardation of boiling by design action and to prevent the retardation of boiling of liquid refrigerant outside the J-shaped pipe.
In addition, typical accumulators aim to preventing only the retardation of boiling of the liquid in a J-shaped pipe. However, such a retardation of boiling may also occur in the liquid which is stored outside the pipe or is separated therefrom. Since a relatively larger amount of liquid is present outside the pipe, the retardation of boiling causes a sudden potentiality of evaporation and a degree of noise to be very high. The risk of the retardation of boiling of the liquid stayed outside the pipe is particularly increased in the accumulator of the refrigerant circuit of the heat pump system.
Additionally, in accumulators known in the related art, it is impossible to actively introduce an evaporation process of liquid in a J-shaped pipe. The stagnant liquid causes the evaporation process to begin over long time intervals without a retardation of boiling due to the relatively slow drop of suction pressure.